Opencode v2: Tool Patch messes up line endings in Windows #54605

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1. opencode-agent commented on Oct 11, 2026

   

   opencode-agentBot

   on Oct 11, 2026 – with OpenCode Agent

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   Thanks for re-filing this for v2, and for the kind words!

   I think this is a duplicate of #45926. It reports the same apply_patch behaviour on v2: lines the patch touches in a CRLF file get LF endings, so the file ends up with mixed line endings. The cause it identifies is still in the current code, and that issue is still open.

   Possible duplicates and related issues, most likely first:

   • apply_patch turns CRLF files into mixed line endings #45926: apply_patch turns CRLF files into mixed line endings (same problem, v2, open)
   • fix(core): preserve CRLF endings when splicing patch hunks #45931: a PR that tried to fix apply_patch turns CRLF files into mixed line endings #45926 by keeping CRLF endings when splicing patch hunks (closed without merging)
   • Tool apply_patch messes up line endings in windows #37090: your earlier v1 report of the same symptom (closed in the v1 cleanup)
   • Line ending issue with fs/write_file in Opencode 2 #50740: line ending problems with fs/write_file over ACP in v2 (a related but different code path)

   Anyone else hitting this can use your plugin, https://github.com/Mac-Moneysac/opencode-fix-line-endings, as a workaround for now.

   The bot will close this issue as a duplicate in 1 day unless you reply explaining how your problem is different. Feel free to add your details to #45926 in the meantime.
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3. Mac-Moneysac commented on Oct 11, 2026

   

   Mac-Moneysac

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   Issue #45926 has been opened vor v1. The corresponding pull request #45931 was implemented for v1 and has therefore been closed. For this reason, I have specifically opened this ticket for v2.
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5. opencode-agent commented on Oct 11, 2026

   

   opencode-agentBot

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   Thanks for the details. I've reproduced this on 2.0.26, and it still happens on the latest dev (727fd603).

   Steps, using a simulated model:

   1. Start with a file app.ts with four CRLF lines.
   2. The model calls the built-in patch tool to change one line and add a new one.
   3. Check the file with cat -A: CRLF lines end in ^M$, LF lines end in $.

   After the patch, every line inside the hunk is LF, including the unchanged context lines, while the untouched line at the end is still CRLF. The file ends up with mixed line endings. The screenshot and recording below show it, and the script below reproduces it.

   The v2 patch code splits and rejoins the file on \n alone, so the model's LF lines replace the CRLF lines they cover. It's ready for a maintainer to look at. In the meantime, your plugin (https://github.com/Mac-Moneysac/opencode-fix-line-endings) is a workaround.

   recording.mp4

   

   Reproduction script (drive.ts)

   // Repro for anomalyco/opencode#54605: the patch tool writes LF line endings into CRLF files.
   // The project starts with a CRLF file. The simulated model calls `patch` to change one line
   // and add a new one, then runs `cat -A` (CRLF lines end in "^M$", LF lines end in "$").
   import { Effect } from "effect"
   import { Llm, OpenCodeDriver } from "opencode-drive"
   
   const patchText = [
     "*** Begin Patch",
     "*** Update File: app.ts",
     "@@",
     " const a = 1",
     "-const b = 2",
     "+const b = 20",
     "+const added = 99",
     " const c = 3",
     "*** End Patch",
   ].join("\n")
   
   export default OpenCodeDriver.use(
     {
       ...(process.env.OC_DEV ? { opencode: { dev: process.env.OC_DEV } } : {}),
       project: {
         git: true,
         files: { "app.ts": "const a = 1\r\nconst b = 2\r\nconst c = 3\r\nconst d = 4\r\n" },
       },
       tui: { recording: true },
     },
     ({ ui, llm }) =>
       Effect.gen(function* () {
         yield* llm.queue(
             Llm.toolCall({ index: 0, id: "call_before", name: "shell", input: { command: "cat -A app.ts", description: "Show line endings before" } }),
             Llm.finish("tool-calls"),
         )
         yield* llm.queue(
             Llm.toolCall({ index: 0, id: "call_patch", name: "patch", input: { patchText } }),
             Llm.finish("tool-calls"),
         )
         yield* llm.queue(
             Llm.toolCall({ index: 0, id: "call_after", name: "shell", input: { command: "echo AFTER; cat -A app.ts", description: "Show line endings after" } }),
             Llm.finish("tool-calls"),
         )
         yield* llm.queue(Llm.text("Done. Lines ending in ^M$ are CRLF, lines ending in $ only are LF."))
         yield* ui.submit("Change b to 20 and add a line after it in app.ts")
         yield* ui.waitFor("Done. Lines ending", { timeout: 60000 })
         yield* Effect.sleep(1500)
         yield* ui.screenshot("after-patch")
       }),
   )

   Run it with opencode-drive: opencode-drive run ./drive.ts. It drives opencode from your PATH; set OC_DEV to the path of an OpenCode checkout to run that from source instead.
6. opencode-agent

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7. neriousy commented on Oct 20, 2026

   

   neriousy

   on Oct 20, 2026

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   Thanks for reporting this on V2 and sharing your workaround. This is the same problem as #45926: patching a CRLF file introduces LF endings, and we're tracking it there. Please subscribe or add a 👍 to that issue; your Windows 11 details and workaround are worth adding there too.
8. neriousy

   closed this as a duplicateof apply_patch turns CRLF files into mixed line endings #45926 on Oct 20, 2026